Researchers study link between weight, risk of breast cancer

10/26/2013 12:04 PM

08/08/2014 10:19 AM

Mother and daughter Angela and Candi Watts were both diagnosed with breast cancer in 2011. After a two-year battle, they are both disease-free, but the war continues.

The new enemy is their waistlines.

Scientists have discovered that excess weight not only raises the risks of getting cancer but the chances that cancer will return. Now, as medical studies seek to determine how much weight loss is needed for a better prognosis – and whether the fat-cancer link can be disrupted in other ways – patients are being encouraged to slim down.

“We need to do this for our health, now more than ever,” said Angela Watts, 59, who is among the first survivors to benefit from a calorie-counting computer program provided by Johns Hopkins Hospital, where she was treated for stage 2 breast cancer. She dropped 5 pounds her first week.

The connection between fat and breast cancer, strongest in those diagnosed with the disease after menopause, is especially troubling given that two-thirds of the national population is overweight. Breast cancer remains the most common type of cancer for women, with more than 200,000 diagnoses and almost 40,700 deaths reported in 2009, the most recent year for which government statistics are available.

Doctors and public health officials have long been promoting lifestyle changes to stave off heart disease and diabetes, but they believe fewer people associate better diets and exercise with cancer prevention.

Cancer patients, meanwhile, face their own hurdles. They might have trouble dieting and exercising because treatment often makes them gain weight while experiencing fatigue and other side effects.

Given those challenges, researchers in Baltimore and across the country are seeking the best ways to change behaviors among those with a diagnosis and those who could be headed down that path.

Lewis Foxhall, who works on cancer-prevention policy at the University of Texas MD Anderson Cancer Center in Houston, said doctors don’t know exactly how much weight loss improves a prognosis.

One often-cited study, published in 2009, tracked only those who had weight-loss surgery, which typically cuts much more body fat than diet and exercise, and keeps the fat off longer. Researchers also believe biological changes resulting from the surgery itself might have helped reduce women’s risk of cancer.

Still, Foxhall, an American Cancer Society board member, recommends that doctors advise all their patients to diet and exercise and that public health officials get the message out.

“We need to pursue the things we know are associated with preventing cancer and help us deal with cancer once we get it,” he said. “We need to address nutrition in the community and physical activity in schools and make sure people can make healthy choices.”

Scientists theorize that obese women have elevated levels of hormones – including insulin, which regulates blood sugar; estrogen, a female sex hormone; and leptin, which helps regulate appetite – that lead to complex biological changes, including inflammation in the body that can promote cancer growth.

Some researchers are looking for ways to disrupt this link.

Dipali Sharma, an associate professor of oncology at Hopkins, wants to eventually develop a pill. After exploring the biology of many compounds, she’s focusing on broccoli, garlic and the magnolia plant, whose properties show promise.

The therapy is a long way off – if it’s possible – but important because “it’s hard to tell someone just to lose a lot of weight,” she said.

“If we know the pathways and the key players, we can develop a pill or capsule that can shut the pathways and tackle the key players and inhibit the link,” Sharma said.

Angela Watts, 59, says the calorie-counting computer program is helping her. She’s been through surgery, chemotherapy and radiation for her breast cancer and she knows that dropping more pounds can reduce the risk of the cancer recurring.

The computer counts calories from her meals and subtracts calories burned from exercising – warning her when she’s approaching her daily 1,500-calorie limit. Watts said she weighed as much as 212 pounds and has a goal weight of 150. Cancer, and her 4-year-old grandson Zhione, Candi’s son, are motivating her, she said.

Watts said she had no symptoms but was diagnosed with breast cancer in May 2011 when she went for a checkup a month after her daughter was diagnosed at the age of 32. The Watts women have a genetic mutation that increased their chances of cancer.

They were treated together at Hopkins and are now focused on diet and exercise. Angela Watts said her daughter, now 34, “doesn’t have as far to go” in losing weight and isn’t participating in the study.

“I always knew I had a weight problem, and losing the weight was something I always wanted but didn’t know how to achieve,” she said. “Counting calories is working for me.”

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